Plantwide control system makes Unix-type power affordable.

A supplier of Unix-based software as brought the power of distributed control to a 32-bit Windows-based system that is affordable, operator-friendly, and truly multi-tasking.

Windows-based control systems are cost-effective and user-friendly in many plastics applications, though until now they have fallen far short of what Unix systems offer in power and flexibility, says Steve DeLonge, Business Development Manager at plastics controls supplier Barber-Colman Co. in Loves Park, Ill. Unix is used to integrate plantwide control and monitoring systems for large mining, steel, petrochemical, paper, pharmaceutical, and power-generation facilities. But Unix-based systems are too costly and require too much user training to be attractive for most plastics-processing plants. "Even a plant with 20 extrusion lines cannot justify the infrastructure expense to support the purchase of a Unix-based system," says DeLonge.

All that is about to change, thanks to a collaboration between Barber-Colman and a sister firm, The Foxboro Co. of Foxboro, Mass. At the NPE show in Chicago next June, Barber-Colman plans to introduce a family of supervisory control and monitoring systems for the full range of plastics processes, including extrusion, injection, and blow molding. The products will combine Barber-Colman's expertise in plastics with Foxboro's Intelligent Automation (I/A) control architecture, which has been Unix based but is now available in a version for the Windows NT operating system. The new system is called the I/A Series for Windows NT. It can run on either Unix or Windows NT hardware platforms within the same system.

POWER AND AFFORDABILITY

The power of Unix lends itself to distributed control systems, which collect and distribute process information from multiple devices to multiple system users. Operating systems familiar to plastics processors, like Windows '95 or 3.1, typically are not robust enough to monitor and control every processing operation and device in a large plant. They also do not provide the same range of features that an open-architecture distributed control system can, DeLonge says.

For example, Unix-based systems have enough power to run multiple control applications quickly and simultaneously. Windows-based systems other than Windows NT are also multi-tasking but not to the same degree. "Whatever control applications are running in the background are frozen in time. If you are running a PID loop but you're not active in that window, it just hangs there," DeLonge explains. "With the I/A Series for Windows NT, when you click off or minimize one application, control functions continue to execute."

On the other side of the coin, most Unix-based plantwide controls have proprietary hardware and software and a starting price around $100,000. DeLonge adds that a Unix-based system is typically not operator friendly nor intuitively understandable like Windows. A Unix system typically requires someone specially trained in Unix to run it.

The I/A Series for Windows NT can run a supervisory control and data-acquisition (SCADA) program, a man-machine interface (MMI) application, total machine control functions, or it can be the base platform for plantwide information automation. The NT I/A system is designed to perform real-time control and conduct trending analysis. "Some Windows-based programs can do data collection and display, but they have a hard time doing control," DeLonge says. The I/A Series for Windows NT is a scaleable system that can control from 1 to 40,000 I/O points. DeLonge claims that Windows NT actually brings more speed to the control program than does Unix.

I/A Series for Windows NT also nixes the need for a Unix expert. "Any process engineer familiar with Windows can learn to run the program in a few hours using a tutorial," says DeLonge.

The new system will be much less expensive than a Unix-based system and will utilize off-the-shelf hardware and software. The new system can run on virtually any Pentium PC with at least 100 MHz clock speed and 64 MB of RAM. DeLonge says he has run the program successfully on a laptop computer. He also notes that I/A Series software drivers have been developed for a number of control hardware platforms, such as Allen-Bradley and Fanuc.

I/A Series for Windows NT can be configured for any scale of control, from a single processing line to plantwide control. DeLonge estimates a price tag of around $2000 as a starting point for a simple control system, comprising the software, operating system, and a device for communicating with the processing machine. The basic system also comes with a software package that includes analytical and trending capability and a user-configurable graphical interface. DeLonge estimates that $4000 will purchase the software to control an entire extrusion line, including all of the downstream equipment. He says the new system will cost about the same as current Windows-based programs but will have the advantages of open architecture, platform independence, scaleability, and advanced control capability.

FLEXIBLE, USER-CONFIGURABLE

By February, Barber-Colman plans to complete its design of 22 plastics application screens for SCADA, MMI, and machine-control functions. The standard screens will be supplied with the new software, although a collection of 12 software engineering tools allows users the option of designing their own graphical displays, icons, and reports. Barber-Colman is also developing touchscreen control capability and programs that monitor machine downtime and analyze causes for it.

While the control software can reside in one central workstation PC, a number of remote PCs can be linked to the system using an Ethernet link or any other standard computer network protocol. Any piece of data can be viewed at more than one screen simultaneously. The software also allows the user to change process setpoints or perform full machine control from a remote location, but this may not be advisable in all applications. For safety reasons, certain control functions such as the manipulation of an injection clamp can be written so as to be performed only at the processing machine. The new series also allows remote access to the system so a user can call up the process from outside the plant to learn about production status or conduct system diagnostics remotely.

Users will be able to connect older equipment that uses relay or discrete electronic controls by first sending information from the device to a data collector, which then sends it to the I/A Series for Windows NT workstation. Barber-Colman has designed one of its MACO controllers to act as such a data link.